Method for producing tobacco web material



Oct. 25, 1949. F. J. sowA ET AL 2,485,670

METHOD FOR PRODUCING TOBACCO WEB MATERIAL Filed June 9, 1942 Fl 6. IF163 REDucTIoN IN SIZE 1/ w T GRINDING (DRY AND/0R WET GRINDING) E V IMIXTURE AND/0R "2 HEAT TREATMENT DISPERSION FoRMATIoN WITH ORWITHOUT ERE V AGITATING HEAT TREATMENT FILM FORMING (LAYERING, wITH OR wITHouTPRESSURE 1 4 cAsTINc, EXTRUDING,ETC.)

FILM FORMING (LAYERING, 7 CASTING, ExTRuDING, we) 5 MO'STURE REMOVALMoIsTuRE REMovAL ,5

g 8 HEAT TREATMENT 3 WITH OR wITHouT PRESSURE FIG. 2

. L Q REDucTIoN IN an I MIXING IN wATER 2 A 1/ (DRY AND/OR WET GRIND NG)HEAT TREATMENT 5 FILM FORMING (LAYERING, .WITH OR wITHouT PRESSURECASTING EXTRUDINIG, ETc.)

FILM FoRMINc(LAYERING, 4 CASTING, EXTRUDING, ETc.) 5 MO'STURE REMOVAL 35FIG. 5 MoIsTuRE REMOVAL INVENTOR FRAN K J. SOWA BY FREDERICK F. TpNETORNEY Patented Oct. 25, 1949 METHOD FOR PRODUCING TOBACCO WEB MATERIALFrank J. Sowa, Cranford, N. J., and Frederick F. Tone, Baldwin, N. Y.,assignors to International Cigar Machinery Company, a corporation of NewJersey Application June 9, 1942, Serial No. 446,366

3 Claims.

This invention relates to improved sheets, webs or films formed fromnatural leafy materials such as tobacco, and to the novel method ofproducing such sheets, webs or films.

While it is not broadl new to manufacture paper and similar sheetmaterial having paper characteristics from tobacco or other like leafystock, it is customary to reduce such stock to paper forming pulp by theuse of chemicals according to conventional paper making technique sothat the fibers of the stock will be separated from their bindingmaterial without degradation thereof and can interlock to provide themat in the finall resulting product. These practices, however, whenapplied to the production of tobacco or like papers have provedunsatisfactory due to the fact that in making such paper, stems orfibers must be added and in reducing the tobacco stock in forming thenecessary tobacco pulp, the processes employed destroy most of theessential and valuable characteristics of tobacco, such as color, tasteand aroma, so that the resulting product is of little value as amaterial for smoking or in the manufacture of smoking articles.

According to our invention we make possible the formation of sheet orpaper like material from natural leafy products with or without fibrousparts thereof, and retain substantially all of the desirable featuresand natural characteristics, such as aroma, taste and color, while atthe same time the sheet material thus produced has adequate strength forprocessing and can be handled as if it were natural tobacco in themanufacture of smokable articles therefrom.

Our invention relates, therefore, to the formation of webs, sheets,films or filaments from natural o'rganic leafy material, such as tobaccoor combinations of one or more kinds of tobacco in the same generalmanner as described in Patent 2,433,877 filed by Franklin H. Wells andFrank J. Sowa, October 9, 1941 for Tobacco sheet material grantedJanuary 6, 1948, and has as its chief object, the production of improvedsheets, webs, films or filaments.

It is an object of our invention to provide a method for producingsheets or webs, films or filaments from natural leafy organic materialsuch as whole tobacco leaves, veins or stems, broken leaf fragments, orany portions thereof in de sired combinations and retain in theresulting product substantially all of the desirable characteristics oftobacco while at the same time at least a part of the undesirableconstituents such as tar and nicotine are reduced.

It is an added object of our invention to produce a novel tobacco sheetmaterial or film with or without interspersed fibers and a method forforming the same wherein tobacco, reduced to a finely divided state in aneutral fiuid medium to form a slurry with or without small tobaccofibers, is subjected to heat treatment with or without pressure eitherbefore or after the tobacco has been reduced to its ultimate size, afterWhich the slurry is formed into webs, sheets or films.

It is an additional object of our invention to produce an improved sheetmaterial, films or filaments of tobacco which is capable of beinghandled or formed into smoking articles and wherein these materials havebetter tensile strength and more resistance to fracturing when foldedthan sheets or films formerly produced.

Our process contemplates the division of the tobacco into fine particlesranging in size from colloidal and larger. While we have found that bestresults are obtained when the tobacco is reduced to a substantiallycolloidal state, particles capable of passing through a sixty meshscreen under some conditions will ive a satisfactory product. The finetobacco particles are mixed preferably in a neutral aqueous medium, suchas water, with or without the retention of fibrous particles so that thenatural flavor and color of tobacco remain substantially unchanged inthe finished product yet wherein because of the subjection of themixture to heat or heat and pressure either before or after grinding,the aroma is improved and certain undesirable constituents of thetobacco are present in lowered quantities in the resulting product.

It is an additional object of our invention to produce thin films, websor filaments from natural leafy organic material such as tobacco, or thelike, and provide a novel method for forming the same with or withoutbinders but wherein if binders or fillers are used the resulting tensilestrength of the material produced will be increased.

Other objects of our invention will be set forth in the followingdescription, it being understood that the above statement of objects isintended generally to explain the same without limiting it in anymanner.

In the accompanying drawings which form a part of this specification,and in which like characters of reference indicate the same or likeparts:

Figure 1 shows a schematic and diagrammatic illustration of a preferredmethod of carrying out our invention;

Figure 2 shows a similar illustration of several 'ceedt'he-volume ofvoids in the mill.

3 related steps of the method illustrated in Figure 1;

Figure 3 shows a similar illustration of a slightly modified method;

Figure 4 shows a similar illustration of a modified method;

Figure 5 shows a sheet of the material made.

The tobacco utilized may be of any suitable kind and size, such forinstance as whole leaves or portions thereof, stems or mixtures of each,or if desired, waste tobacco such as clippings, dust, chips and so forthmay be used. For best results we have found that preferably the tobaccoshould be fairly dry, that is, contain moisture, say not in excess offive per cent, although this is not a limiting factor since obviouslythe tobacco can be reduced to the desired size and state if the moisturecontent is greater.

The sheet forming material, such as tobacco, also may be in any desiredcondition, as for instance, whole leaves or portions thereof, stems ormixtures of each, and since most of the natural physical characteristicsof tobacco leaves as such are lost in the practice of our invention, wealso contemplate the use of waste tobacco such as i clippings, dust,chips, and so forth, which result "from the manufacture of cigars,cigarettes and other tobacco articles.

The tobacco being processed may be reduced to proper size, as indicatedat i or la in Figures -1 and '3, respectively, either by dry grinding orwet grinding, or a combination of steps including both dry and wetgrinding.

When tobacco is dry ground, a selected quantity is preferably driedtoremove most of the moisture retained therein, after which it is brokenup into small pieces in any suitable manner. It has been found that drygrinding proceeds faster and more satisfactorily when the moisturecontent is reduced below five per cent. Any suitable device may beemployed "for reducing the broken up dried tobacco to final size.

For instance, the tobacco may be placed in a ball mill and ground tocolloidal, or substantially colloidal size, or fine powder capable ofpassing through an eighty mesh screen. In some instances powder capableof passing through a sixty mesh screen may be used, but generally Weprefer the finer sizes. This method of grinding, however, is relativelyslow and the amount of'time consumed varies according to the quantity oftobacco selected for grinding, the size of the mill and the balls orpebbles used therein, and the speed of operation of the mill.

For optimum results the charge should not ex- The amount of timerequired is also a function of the size and condition of the tobaccobefore it is placed in the mill. For instance, if the material beingcomminuted is small particle size at the outset,

less time will be required than if the material is in the form of brokenup leaves and stems.

If more rapid material grinding is preferred, a plate or disc typecolloidal mill may be used, in which case a selected quantity of tobaccoor other leafy material can be reduced advantageously to extremely finesize in a matter of min-- utes.

If the tobacco or other natural leafy material selected for formationinto sheets or films, is to' be wet ground as at i in Figures 1 and 4,and id in Figure 3, a selected quantity of tobacco is preferably brokenup in order'to expedite its reduction, placed in a grinding devioe,-suchas a ball mill, and an aqueous medium, such as=water is 'faces or formedinto filaments.

added thereto to establish a suitable ratio of tobacco to water, say of1:8 or 1:6 by weight depending upon the type of tobacco. Greater orlesser ratios can be used advantageously dependim on the type oftobaccos being ground and the viscosity of the resulting slurry desired,the thinner the sheet desired the less viscous the slurry,

The mixture is ground for a period suificient to reduce the solidmaterial to extremely fine size, wherein some, and preferably thegreater part, of the particles are in a colloidal state. It has beenfound that the grinding time varies over a considerable range, and thatwhen this mixture is groundfor a period ranging between six and eighthours in a 1 gallon mill, using inch balls at-45-50 revolutions perminute,

advantageous results are obtained. In some instances there may remainsmall fibrous particles of tobacco due to the presence of veins andstems as indicated at 2 in Figure 1. This, however, is not objectionablebecause in most instances such minute fibrous particles appear'to have agood effect upon the finished film or sheet and add to its strength.

We have also found that a good method of grinding tobacco is to wetgrind whole tobacco leaves for one or more hours and then'pass'the grindthrough a screen. When such a grind has been prepared and screened, theunground portions consisting principally ofstems and veins,

are removed and the filtrate consisting of the "better portions of theleaves can then be wet ground in a ball mill, as above described, for asuitable time as described. This forms a good slurry which can beextruded, spread out or centrifugally applied to suitable sheet formingsur- The proportions of tobacco and water used in the above case runsubstantially the same as when a charge of powdered tobacco and water isintroduced into a ball mill.

The material may also be subjected to both dry and wet grinding. If thistypeof grindin is resorted to, selected tobacco is preferably dried andthen ground either in a disk type colloid mill rapidly in a few minutesor more slowly, about three hours, in a ball mill, as describedhereinabove. When the material has been reduced to roper size, saycapable of passing through a sixty or eighty mesh screen or smaller, itis introduced into a second grinding device, such as a ball mill or leftin the first mill and mixed with a-suitable quantity of fluid in orderto prepare it for a wet or final grinding. Any fluid preferably neutral'in nature, such as water or dilute ethyl alcohol,

with which a colloidal dispersion will take'place, can be used. It isimportant that a fluid be chosen which will have little or nodeleterious effects upon the tobacco or otherwise change its normalcharacteristics insofar as taste, odor and color are concerned, sincethey are carried over into our final product and retained therein. Waterforms a very satisfactory medium and is usually used in an amountsuitable to form a fluid the capacity of the ballmill, if a ball mill isselected as the grinding mechanism,- the size of balls and speed ofoperation of the mill. We have found that a ball mill is a satisfactorydevice to use in carrying out this step of our process and that with a1% gallon mill containing 800 cubic centimeters of water and 100 gramsof tobacco constituting the wet grind mixture or slurry, the timerequired to reduce the charge of powdered tobacco to fine particles orto sheet or film forming size and state ranges between one and tenhours, and that on an average of six hours has proven to be anadvantageous period. If anything, the material ground for the longerperiod of time results in a denser sheet.

It has also been found advantageous under some conditions to makeslurries having fibrous tobacco particles intermixed therewith. Suchslurries are formed in any manner, such as by the addition of a quantityof fibrous tobacco particles of small size added in any required quantitdependent upon the amount of fibrous particles desired in the finalsheet or film; or particles can be added by grinding together in any ofthe methods described above, a mixture of tobacco leaf portions andstems, and/or veins, which in the period of grinding will not beconverted to col-- loidal size but will still retain fibrouscharacteristics. When this type of slurry is subjected to heat or heatat atmospheric or greater heat at elevated pressures, as describedhereinafter, the finely ground and colloidal tobacco particles form asol with the fibrous particles interspersed therethrough and whenlayered into films or sheets or filaments, the contained fibers add tothe tensile strength of the resulting product.

A good sheet results from grinding 75' parts of dry tobacco powder with600 parts of water in a ball mill for four hours after which time 25parts of leafy tobacco, which contains veins, and 200 more parts ofwater are added to the mill making the tobacco water ratio substantially1:8 by weight, and the whole mixture is ground for two to three hoursadditional depending upon the required thinness of the final product. Inthe second grinding phase, practically all of the leafy portions of thetobacco are converted into extremely fine or colloidal particles exceptthe vein portions thereof which remain as very small fibrous particleswhich add to the tensile strength of the final product. Obviously thequantity of tobacco fibers present in a slurry produced in the abovemanner will vary according to the type of tobacco leaves or leafymaterial subjected to grinding. However, as far as the above proportionsare concerned, a few fibrous particles more or less have no markedinfluence on the sheets or films produced from such a slurry.

If a slurry is produced by mixing together a selected quantity of groundtobacco and water in a ratio of say 1:6 or 1:8 by weight, or otherproportion such as described above, an intimate suspension can beobtained by mixing the material mechanically in any known manner asdesired, theparticles may be dispersed throughout the liquid phase byagitating with steam, both to effect a proper dispersion and to assistin the subsequent formation of films and the like as describedpreviously.

The mixture of tobacco and water is next subjected to heat atatmospheric pressure or to greater heat under elevated pressure as bytreating the tobacco or slurry in an autoclave for a period of timesumcient to hydrate and swell the particles until substantially ahydrosol is formed, especially insofar as the finest or colloidalparticles are concerned. Also, during the time of 6 hydration there issome hydrolysis taking place and it is from this action that it isbelieved that the heat accelerates the hydration of the tobaccoparticles and also accelerates the limited amount of hydrolysis of suchmaterials contained in tobacco as glucosides, thereby increasing thearoma of the resulting tobacco product and greatly enhancing itsdesirability for use in form ing smoking tobacco articles. Thesubjection of the mixture to heat at atmospheric pressure or to a higherheat at elevated pressures, as indicated by numeral 3 in Figures 1, 2,and 3, is also believed to reduce somewhat the total tar and nicotinecontent in the smoke given off when smoking articles made from our sheetmaterial are consumed. The resulting sheets, films or filaments alsoretain their general characteristic tobacco color and fiavor.

Heat at atmospheric pressure or higher heat at elevated pressuretreatment may be given either before the tobacco is converted into aslurry as illustrated at 3a in Figure 4 or after. If it is resorted toafter the formation of the slurry, it is preferred to place a quantityof the slurry in a pressure cooker and cook it therein at a pressure offifteen pounds per square inch for a period of three hours at 250 F.water vapor temperature. Other pressures and cooking periods can be usedadvantageously. For instance, if the pressure is increased then thedesired result is effected in a shorter time. For instance, if sixtypounds per square inch be used, the necessary cooking will be effectedin about fifteen minutes. Lower pressures are usually used and have beenfound to give best results. If pressure is de-. creased below fifteenpounds :per square inch, a period of time greater than three hours isnecessary. Also, if desired, the mixture can be cooked at normalatmospheric pressure by heating in a reaction flask connected to areflux condenser for about five hours and satisfactory results areobtained. During the heat treatment of the slurries, it is advantageousto agitate the slurry or suspension as by shaking or stirring, or in anyother suitable manner such as bubbling live steam into the suspensionbecause this breaks up particles tending to conglomerate and assists inthe complete hydration of the individual particles of the suspension.

The slurries treated in the above manner are formed into sheets, webs orfilaments, as indicated by numeral 3, Figures 1-4 much in the manner astaught in the above referred to Wells and Sowa Patent 2,433,877, as bypouring the slurry over film forming surfaces, or spraying on a filmforming surface with a spray gun, or by the use of suitable extrudingmechanism, or by applying onto the interior of a rotating cylinder. Thematerial is dried until it is in a fiexible, pliable condition cap-ableof being used in formation of binders, wrappers and as parts of cigars,and other smoking or tobacco articles. This step may be indicatedgenerally at 5 in Figures 1-4 inclusive. It is usually best to dry thelayers or sheets in a somewhat humid atmosphere since the product issomewhat more flexible than when it is dried rigid in a dry atmos phere.However, if the latter method is resorted to, humidifiers may beemployed to restore the flexibility. The material produced in accord--ance with our invention may be bent or folded with considerable successand usually will not fracture along the line of bend, and especially isthis so with respect to the films formed from slurries containing smalltobacco fibers dispersed L7 "therethrough treated with heat atatmospheric pressures :or higher heat at elevated pressures. Filamentsmay be formed from the sheets or "webs in any desired manner; suchascutting, or

they may .be formed "by extruding the slurry through suitableconventional devices. The resulting .productsare dense, tough and havesuitable strength, flexibility and other desirable characteristics oftobacco leaves and may be 'put to any similar use.

Slurries havingfibrous tobacco particles inter- -mixed'therewith arealso. formed byaddition of a quantity of fibrous tobacco particles or bygrinding together in any of the methods described hereinabove amixture-of tobacco leaf portions and stems and/or veins, in whichthe:period of grinding mentioned will not destroy the fibrouscharacteristicsof the fibrous material althoughthe fibers will bereduced in size and 'length. treated1to heat at atmospheric pressure orhigher heat atelevated pressures previous to being ground or if theresulting slurry is subjected-to 1heat as described hereinabove, thefinally ground and colloidal tobacco particles form a sol with thefibrous-particles interspersed therewith. .As describedhereinabove, whenthis type of sol is lay- .ered into films or sheets, the containedfibers add to the-strength of the resulting product. It

Will'be appreciated thatfibers may be retained in I .slurries' if thegrinding time .is controlled. A good slurryv resultsin which the leafymaterial is practically entirely destroyed except for minute fibrousparticles of very short length, which remain because of-the lack of thecomplete grind- .ilflg :oi the veins or stems. Whensuch a slurry -iscast or sprayed .or otherwise applied to a film forming surface, astrong product results. As .mentioned above any suitable ratio oftobacco to "fluid .rnediumby weightimaybe used instead of 1:8 ratiodescribed above depending upon the thickness of the final sheet or filmto be formed; the less .fluid medium used the thicker the sheet andvice'versa using the same amount of slurry. The quantity of fibrousparticles present in-slur- -ries produced, as above described, will varyaccording to the type of tobacco since obviously some tobaccos have moreveins or stems per leaf than do others.

'Peptizing agents may be added to the slur- Gluconic acid, tannic acid,dilute sodium hydroxideor any other suitablematerial may be usedadvantageously.

In some instances it is advantageous to add binders, fillers andplasticizers to the tobacco slurry resulting from grinding tobacco inwater J in order to increase the strength of the resulting film producedbefore or after subjecting to heat at atmospheric pressure 'or greaterheat at elevated pressures.

Suitable materials are methyl ether of cellulose sold under thetrade-mark of Methocel, or ethyl ether of cellulose known as Ethocel, orgelatine or polyvinyl alcohol. These materials when used in the properquantity, usually of 1 per cent by weight, have no obj otionable effectupon the finished product insofar as handling and use in tobaccoproducts are concerned.

If thematerialbeingground has been- Number tion have been described, itis to be understood that the invention is not confined to the specificmethod steps 'forcarrying out themethod herein set forth, by way ofillustration, as it is apparent that manychanges and variations may bemade therein, by those skilled in the :art, without departing from thespirit of the invention or exceeding the scope of the appended claims.

What is claimedis:

l. The method of forming tobacco sheet -material which comprises dryinga selected quantity of tobacco, grinding to reduce said quantity oftobacco to small size, reducing said tobacco'in water to form a slurrycontaining colloidal tobacco, subjecting said slurry to heat underfifteen pounds pressure per square inch at a water vapor temperatureapproximately 250 F. for azperiod ranging betweenthree and six hourstoform a hydrosol, applying said hydrosol to a film forming surface andforming a thin layer thereon, and extracting moisture from said layer toform sheet material.

2. The step in forming'tobacco sheet material from a suspension ofground tobacco'inafiui'd medium containingcolloidal-tobaccowhich:comprises subjecting said suspension to fifteenpounds pressure per square inch at a water vaportemperature notexceeding 250 F.

3. The step in forming tobacco sheet .material from a colloidaldispersion of tobacco which comprises subjecting'said dispersion tofifteen pounds pressure persquare inch at a Water vapor temperature notexceeding 250 .F. for a period not exceeding six hours.

FRANK J. SOWA. FREDERICK F. TONE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date Dixon Sept. 27,11859 Stayman May 7,"1867 Consuegra Feb, 2,1869 Bolles July22, 1879 Funke Aug. 23, 1881Bennett Aug. 10, 1886 Brunswig Apr."*9,1899 Butler Sept. 3, 1-907Capehart Dec. 3,1907 Diskin Mar.-9, 1909 Sarti'g Aug. 1, 1911 Maier July22, 1913 Eichmann 'Jan. 14,1936 Schorger May 25,1943 Wells et al Jan.6,1948

FOREIGN PATENTS Country Date Germany Aug. 10, 1928 Great Britain 1856Great Britain Nov."25, l926 OTHER REFE RENCES General Chemistry, byDeming, 4th Edition, published by John Wiley &'Sons, page 4'73. (Copy inDiv. 2.)

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